This invention relates to lawn mowers and more particularly to mowers with mower decks outboard of their drive units which can be tilted upward.
Heretofore it has been known to mount mower deck assemblies on drive units, prime movers or tractors having power takeoffs which provide rotational drives for the blade or blades within the deck. Such combinations have included means for raising the mower deck while it is carried by the drive unit, tractor or prime mover. Typically, decks outboard of the drive unit have been pivoted to the drive unit.
Hicks U.S. Pat. No. 4,307,561 of Dec. 29, 1981 for "Blade Housing Lift for Riding Mower" discloses a deck assembly pivotally mounted ahead of a vehicle chassis at the rear of the assembly with a hydraulic cylinder for lifting the assembly for non-mowing transport. The cylinder has a piston rod with a pulley at its end engaging the bight of a loop of flexible chain, one end of which is secured to the chassis and the other end of which is secured to the deck assembly, so that extension of the rod raises the bight of the chain and deck. The arrangement permits raising the deck assembly about its chassis pivot support to an inclination of about thirty degrees to the ground.
Kuhn U.S. Pat. No. 4,441,306 of Apr. 10, 1984 for "Implement Working Height - Adjustment Mechanism" shows a mower of the type disclosed by Hicks with a direct link of a lift cylinder piston arm pivotally connected to a support arm for the mower deck assembly. Kuhn's arrangement also limits the lifted position of the deck assembly relative to the ground. A later U.S. Pat. No. 4,563,019, of Kuhn et al. has a similar structure with limited upward pivotal motion of the deck assembly to less than a thirty degree inclination to the ground.
Witt et al. U.S. Pat. No. 4,325,211, of Apr. 20, 1982 for "Floating Deck for Rider Mower" shows a cutting unit suspended from a traction unit by a forwardly extending frame which has limited upward pivotal movement on the traction unit for transport purposes.
It is also known in the construction of ditch bank mowers to pivot mower deck assemblies at the side of the traction unit along the adjacent deck side and to adjustably lift the deck assembly wings by hydraulic cylinders.
Davis et al. U.S. Pat. Nos. 4,395,865 and 4,429,515 of Aug. 2, 1983 and Feb. 7, 1984 respectively disclose self-propelled lawn mowers having a multiplicity of rotary cutting blades below a main deck assembly and wings on the main deck sides containing blades. The wings are hinged to the main deck at their sides adjacent the main deck and parallel to the longitudinal or normal travel advance axis of the traction unit and the main deck is arranged for limited upward pivotal movement relative to the traction unit for transport as described above.
The aforenoted typical prior art each provided a mower deck assembly having limited upward motion around a pivot in the case of mower decks pivoted along axes normal to the line of travel of the drive unit, particularly where such decks are mounted ahead of the drive unit. Maintenance of mower deck assemblies, their driving mechanisms and their blades has required inverting the drive unit and the mower deck assembly unit, or working on the unit while in a prone or nearly prone position even with the deck assembly raised to its inclined position, or disassembly of the mower assembly unit from the drive unit. This inconvenience in servicing results in a tendency to neglect maintenance, a substantial effort in performing maintenance, and lost time in such performance.
In accordance with this invention, the underside of the mower deck assembly is made readily and conveniently accessible by arranging the deck assembly so that it can be inverted to reveal its underside and mower blades without disassembly of the machine.
Deck assemblies are mounted on a drive unit outboard of the drive unit on a linkage pivotally connected to the drive unit and to the deck so that the deck can be raised from the terrain being mowed. The pivotal connections have parallel pivot axes and can be at the ends of a pair of arms forming the support linkage so that the deck is elevated by rotating the arms around their pivot axis to the drive unit. Arm length and the relationship of the deck to the drive unit structure permit the deck to be raised to an extent enabling it to be pivoted around the pivot axis of the pivotal connections between the arms and the deck from a generally horizontal position to or beyond a generally vertical position whereby the underside of the deck and the rotary mower blade or blades mounted thereon are exposed for servicing from above and outboard of the deck assembly-drive unit combination.
The rotated or upwardly tilted deck assembly is maintained in that state for servicing by terrain engaging elements on that portion of the deck proximate the drive unit when the deck is in mowing position which are moved outboard of a vertical plane containing the pivotal connection of the arms to the deck in the upwardly tilted position. The terrain engaging elements cooperate with the deck support pivots to form a gravitational moment tending to rotate the deck further toward a fully inverted position thereby providing an over center means of retaining the tilted position of the deck assembly. In order to facilitate this tilting motion, the pivotal connection between the drive unit and arms, the length of the arms, and the structure of the deck assembly and the drive unit affords sufficient freedom of lifting motion of the deck assembly to clear the terrain beneath the deck with the terrain engaging elements when the deck general plane is perpendicular to the terrain.
A rotary drive for the mower blade or blades beneath the deck is continuously engaged for the mowing position, the raised position, and the tilted position of the deck assembly. A drive shaft on the drive unit is arranged for rotation about an axis coaxial with the pivot axis of the deck assembly support linkage pivotal connection to the drive unit. A drive shaft on the deck is arranged for rotation about an axis coaxial with the pivot axis of the pivotal connection between the deck and the support linkage. A flexible closed loop drive linkage such as a chain with sprockets on the two drive shafts or a V-belt and pulleys on those shafts drivingly couples the blade or blades for rotation as through a gear box on the deck assembly having an output shaft through the deck to which the mower blade is secured.
A deck assembly and mounting arrangement for a front mounted mower deck assembly on a drive unit is arranged so that the deck can be rotated to a position exposing its undersurface, advantageously at least through an arc of ninety degrees. This permits the assembly to be cleaned, and the drive and blades to be inspected and if necessary repaired or replaced while the deck assembly and the drive unit remains assembled and standing on ground.
In a front or rear mounted mower deck assembly according to this invention, the deck assembly is pivotally mounted on support arms pivotally connected to the drive unit chassis with the pivot axes at the chassis and deck assembly parallel to the support surface for the drive unit, the ground, and normal to the fore-and-aft longitudinal axis of the drive unit, the normal driving direction. The deck pivots are located in a plane normal to the ground and near the center of gravity of the deck assembly so that the raised deck can be pivoted around its pivots to an over center position in which it will be maintained by gravity during servicing.
While the drive unit can be clutched to the blade drive with interlock controls to declutch the drive when the deck assembly is raised and/or pivoted to expose the blades upwardly, a convenient safety interlock is utilized which stops the drive motor when the machine operator leaves his seat on the drive unit if the clutch is engaged.